LCD device having scanning lines and common lines

ABSTRACT

An active matrix LCD device includes a TFT panel, a counter panel and liquid crystal interposed therebetween. The TFT panel includes a plurality of scanning lines and a plurality of common lines formed in one layer and extending in a row direction, and a plurality of signal lines extending in a column direction. A coupling line for coupling the common lines together is disposed outside the pixel array of the TFT panel, such as in a TCP mounted on the TFT panel and mounting thereon a driver IC for driving the scanning lines.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a divisional of application Ser. No.09/965,566 filed on Sep. 27, 2001, now U.S. Pat. No. 6,930,741.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a liquid crystal display device havingscanning lines and common lines and, more particularly, an LCD devicehaving an improved structure for applying a common potential to commonlines extending parallel to scanning lines.

(b) Description of the Related Art

Liquid crystal display (LCD) devices of an active matrix driving mode(referred to as active matrix LCD devices hereinafter) are increasinglyused as flat panel display devices for personal computers or televisionsets. Referring to FIG. 1A, a typical active matrix LCD device,generally designated by numeral 90, includes a TFT panel 92 defining apixel array thereon and a counter panel 94 opposing the TFT panel 92,and liquid crystal disposed between the TFT panel 92 and the counterpanel 94. The LCD device 90 also includes a plurality of vertical driverICs 96 each mounted on a film tape for driving a plurality of scanninglines in the pixel array, and a plurality of data driver ICs eachmounted on a film tape for driving a plurality of signal lines in thepixel array.

A conventional active matrix LCD device is described in PatentPublication JP-A-7-36061, for example. Referring to FIG. 1B, the TFTpanel 70 of the conventional active matrix LCD device described thereinincludes a glass substrate or transparent substrate (not shown), aplurality of scanning lines 72 extending in a row direction on the glasssubstrate, a plurality of signal lines 74 extending in a columndirection on the glass substrate, and an array of pixels disposed atrespective intersections between the scanning lines 72 and the signallines 74. A plurality of common lines 78 each extending parallel to acorresponding one of the scanning lines 72 are also disposed on theglass substrate. A silicon nitride film is interposed between thescanning lines 72 and the signal lines 74 for electric insulation.

Each pixel includes a thin film transistor (TFT) 76 as a switchingelement, a pixel electrode 80 connected to the source of the TFT 76, anLC element expressed as a capacitor 81 connected between the pixelelectrode 80 and a counter electrode 83, and an additional capacitorelement 82 connected between the pixel electrode 80 and the common line78. The gate of the TFT 76 is connected to a corresponding scanning line72, whereas the drain of the TFT 76 is connected to a correspondingsignal line 74.

The proximal end of each scanning line 72 is connected to a scanningterminal 84 which is disposed for connection to a vertical driver ICmounted on a TCP (tape carrier package). Both the ends of each commonline 78 is connected via respective through-holes 86 to respectiveoverlying coupling lines 88A and 88B, which is disposed to apply a fixedpotential or the ground potential equal to the potential of the counterelectrode.

The scanning lines 72 and the common lines 78 are formed by patterning asingle conductor layer. Each scanning line 72 intersects an overlyingcoupling line 88A, with a silicon nitride film interposed therebetween.The steps for forming the overlying coupling lines 88A and 88B andthrough-holes 86 for connecting the common lines 78 to the overlyingcoupling lines 88A and 88B complicate the fabrication process for theLCD device in the conventional technique.

SUMMARY OF THE INVENTION

In view of the above, it is an object of the present invention toprovide an active matrix LCD device which is capable of reducing theprocess steps for fabricating the TFT panel by obviating or simplifyingthe process steps for forming the overlying coupling lines and thethrough-holes therefor.

The present invention provides, in a first aspect thereof, an activematrix LCD device including a TFT panel, a counter panel and liquidcrystal disposed therebetween, the TFT panel including:

a transparent substrate;

a plurality of scanning lines overlying the transparent substrate toextend in a row direction;

a plurality of signal lines overlying the transparent substrate toextend in a column direction;

a plurality of common lines each corresponding to one of the scanninglines to extend in the row direction parallel to the one of the scanninglines, the scanning lines and the common line are formed in a singlelayer;

an array of pixels each disposed at an intersection between one of thescanning lines and one of the signal lines, the common lines havingextending portions extending outside an area for the array of pixels;and

a coupling line coupling the extending portions together and formed inthe single layer.

The present invention also provides, in a second aspect thereof, aliquid crystal display (LCD) device including a TFT panel, a counterpanel and liquid crystal interposed therebetween, the TFT panelincluding:

a transparent substrate;

a plurality of scanning lines overlying the transparent substrate toextend in a row direction;

a plurality of signal lines overlying the transparent substrate toextend in a column direction;

a plurality of common lines each corresponding to one of the scanninglines to extend in the row direction parallel to the one of the scanninglines, the scanning lines and the common line are formed in a singlelayer;

an array of pixels each disposed at an intersection between one of thescanning lines and one of the signal lines; and

a coupling line extending in the column direction, the coupling lineincluding a conductive paste coupling the common lines together.

The present invention also provides, in a third aspect thereof, a liquidcrystal display (LCD) device including a TFT panel, a counter panel, andliquid crystal interposed therebetween, the TFT panel including:

a transparent substrate;

a plurality of scanning lines overlying the transparent substrate toextend in a row direction;

a plurality of signal lines overlying the transparent substrate toextend in a column direction;

a plurality of common lines each corresponding to one of the scanninglines to extend in the row direction parallel to the one of the scanninglines, the scanning lines and the common line are formed in a singlelayer; and

an array of pixels each disposed at an intersection between one of thescanning lines and one of the signal lines,

the TFT panel mounting thereon at least one driver block including afilm member, a driver IC mounted on the film member for driving thescanning lines, and a coupling line for connecting the common linestogether.

In accordance with the active matrix LCD devices of the presentinvention, since the coupling line for coupling the common lines isdisposed outside the area for the pixel array on the TFT panel, at leastone photolithographic etching step can be obviated in forming thecoupling line, whereby the cost of the LCD device can be reduced.

The above and other objects, features and advantages of the presentinvention will be more apparent from the following description,referring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic perspective view of a typical active matrix LCDdevice.

FIG. 1B is a circuit diagram of a TFT panel of a conventional activematrix LCD device.

FIG. 2 is a partial top plan view of a TFT panel of an active matrix LCDdevice according to a first embodiment of the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG. 2.

FIG. 4 is a sectional view taken along line IV-IV in FIG. 2.

FIG. 5 is a partial top plan view of a TFT panel of an active matrix LCDdevice according to a second embodiment of the present invention.

FIG. 6 is a sectional view taken along line VI-VI in FIG. 5.

FIG. 7 is a sectional view taken along line VII-VII in FIG. 5.

FIG. 8 is a partial top plan view of a TFT panel of an active matrix LCDdevice according to a third embodiment of the present invention.

FIG. 9 is a sectional view taken along line IX-IX in FIG. 8.

FIG. 10 is a partial top plan view of a TFT panel of an active matrixLCD device according to a fourth embodiment of the present invention.

FIG. 11 is a sectional view showing a COF used for the TFT panel of FIG.10.

FIG. 12 is a sectional view taken along line XII-XII in FIG. 10.

FIG. 13 is a sectional view taken along line XIII-XIII in FIG. 10.

FIG. 14 is a schematic circuit diagram showing the connection for theCOF shown in FIG. 11.

FIG. 15 is a partial top plan view of a modification of the TFT panel ofFIG. 10.

FIG. 16 is a partial top plan view of a TFT panel of an active matrixLCD device according to a fifth embodiment of the present invention.

FIG. 17 is a sectional view of a TCP used in the TFT panel of FIG. 16.

FIG. 18 is a sectional view taken along line XVIII-XVIII in FIG. 16.

FIG. 19 is a sectional view taken along line XIX-XIX in FIG. 16.

FIG. 20 is schematic circuit diagram showing the connection for the TCPshown in FIG. 17.

FIG. 21 is a top plan view of the pixel in the TFT panel of FIG. 2.

FIG. 22 is a sectional view taken along line XXII-XXII in FIG. 21.

FIG. 23 is a sectional view taken along line XXIII-XXIII in FIG. 21.

FIG. 24A is a top plan view of the TFT panel of FIG. 2 at a first stepof fabrication thereof.

FIG. 24B is a sectional view taken along line B-B in FIG. 24A.

FIG. 24C is a sectional view taken along line C-C in FIG. 24A.

FIG. 24D is a top plan view of the TFT panel of FIG. 2 at a second stepof fabrication thereof.

FIG. 24E is a sectional view taken along line E-E in FIG. 24D.

FIG. 24F is a sectional view taken along line F-F in FIG. 24D.

FIG. 24G is a top plan view of the TFT panel of FIG. 2 at a third stepof fabrication thereof.

FIG. 24H is a sectional view taken along line H-H FIG. 24G.

FIG. 24I is a sectional view taken along line I-I in FIG. 24G.

FIG. 24J is a sectional view taken along line H-H in FIG. 24G after afourth step.

FIG. 24K is a sectional view taken along line I-I in FIG. 24G after thefourth step.

PREFERRED EMBODIMENTS OF THE INVENTION

Now, the present invention is more specifically described with referenceto accompanying drawings, wherein similar constituent elements aredesignated by similar reference numerals.

Referring to FIG. 2, a TFT panel of an active matrix LCD device,generally designated by numeral 10, according to a first embodiment ofthe present invention includes a glass substrate 12, a plurality ofscanning lines 14 extending in a row direction on the glass substrate12, a plurality of common lines 16 extending parallel to the scanninglines 14 on the glass substrate 12, a pair of coupling lines 18A and 18Beach extending in a column direction for connecting the common lines 16together at an end of the common lines 16, and a plurality of signallines (not shown) extending in a column direction. The configuration ofthe LCD device of the present invention is similar to the conventionalLCD device shown in FIGS. 1A and 1B except for the configuration of thecoupling lines 18A and 18B for connecting the common lines 16 togetherand the terminals of the scanning lines 14.

Each scanning line 14 is independently connected to a vertical driver ICthrough a terminal 20 in the space between the coupling lines 18A and18B, to apply scanning signals to the gates of a corresponding row ofthe TFTs. This configuration allows each scanning line 14 not tointersect either of the coupling lines 18A and 18B.

The pair of coupling lines 18A and 18B extend in the peripheral area ofthe TFT panel, i.e., outside the area for the pixel array. The couplinglines 18A and 18B form a loop circuit in association with the commonlines 16 for applying an equi-potential to the common lines 16substantially without a time difference. The coupling lines 18A and 18Bare associated with and connected to a pair of terminals 24A and a pairof terminals 24B, respectively, through which a common potential isapplied.

The conductor film including the scanning lines 14, the common lines 16and the coupling lines 18A and 18 B is formed on the glass substrate 12and has a two-layer structure including an Al film and an overlying TiNfilm.

Referring additionally to FIG. 3, each of the terminals 20, 24A and 24Bis formed as a large-width portion of the scanning line 14 or the commonline 16, and exposed from the gate insulating film 25 and thepassivation film 26 through a through-hole 28. The gate insulating film25 and the passivation film 26 both made of silicon nitride cover thescanning lines 14 and the common lines 16 in the area other than theterminals 20, 24A and 24B disposed outside the area for the pixel array.

In the above example of the first embodiment, the coupling lines 18A and18B extend outside the area for the scanning line 14, as describedabove. Thus, upon separation of the product TFT panels 10 of the presentembodiment by scribing the glass substrate 12, the product TFT panels 10are subjected to cutting along scribe lines extending adjacent to theouter side lines of both the coupling lines 18A and 18B. The portion ofthe glass substrate separated from the product TFT panel is discarded.

In an alternative of the above embodiment, a single coupling line may bedisposed for connecting the common lines together. In this case, a shuntcoupling line may be provided extending from the scanning lines 14, theshunt coupling line opposing the single coupling line for the commonlines 16 with an intervention of the scanning lines 14. The shuntcoupling line is separated from the product TFT panel upon scribing forthe product TFT panel.

In the above embodiment, although four terminals are provided for thepair of coupling lines, two or three terminals may suffice the productTFT panel. Further, although an in-plane switching (IPS) mode TFT panelis exemplified in the present embodiment, the present invention can beapplied to a twisted-nematic (TN) mode LCD device having a common stragestructure.

The structure in which the coupling lines 18A and 18B are formed as acommon layer with the common lines 16 allows reduction of the number ofthe process steps for the LCD device.

Referring to FIGS. 5, 6 and 7, a TFT panel of an active matrix LCDdevice, generally designated by numeral 30, according to a secondembodiment of the present invention is similar to the first embodimentexcept for the configuration of one of the coupling lines and connectionbetween the one of the coupling lines and the common lines. Morespecifically, a coupling line 32A in the present embodiment is similarto the coupling line 18A in the first embodiment, whereas a couplingline 32B in the present embodiment extends perpendicular to andintersects the scanning lines 14 and the common lines 16 at the area forthe pixel array.

The coupling line 32B is made of a conductive tape and is connected tothe common lines 16 via the via-plugs in the through-holes 34penetrating the gate insulation film 25 and the passivation film 26, asshown in FIG. 7. The via-plugs are formed by conductive paste filled inthe through-holes. The coupling line 32B is thrust or forced toward theTFT panel for electric connection. The conductive tape is made of“Sintron (trade mark)” supplied from Sinto Paint Co. The coupling line32B is connected to terminals 24B of the common lines 16 viathrough-holes 34 and the common lines 16. The conductive tape includes afilm member and a conductive layer made of conductive paste (orconductive adhesive) formed thereon.

The terminals 20, 24A and 24B are similar to those in the firstembodiment, and as shown in FIG. 6, is formed as large-width portions ofthe scanning lines 14 and the common lines 16, the large-width portionsbeing exposed from the gate insulating film 25 and the passivation film26 through through-holes 28.

In the present embodiment, since the coupling line 32B is disposedwithin the are for the pixel array or the area for the scanning lines14, the product TFT panels are scribed along a cut line extending alongthe column of the scanning terminals 20. Although not illustrated inFIG. 5, the scanning lines 14 may be connected to a shunt coupling linedisposed outside the scanning terminals 20. In this case, the shuntcoupling line is separated from the product TFT panel upon scribing.

In the present embodiment, the structure wherein the coupling line 32Aand the common lines 16 are formed by patterning a single conductorlayer, and wherein the coupling line 32B is formed by thrusting theconductive tape allows the number of process steps such asphotolithographic and patterning steps to be reduced.

Referring to FIGS. 8 and 9, a TFT panel of an active matrix LCD device,generally designated by numeral 40, according to a third embodiment ofthe present invention is similar to the second embodiment except for theconfiguration of the coupling line 42B. More specifically, the couplingline 42B in the present embodiment is made of silver (Ag) paste, whichis electrically connected to the underlying common lines 16 viathrough-holes 34 penetrating the gate insulating film 25 and thepassivation film 26.

The silver paste is made of evaporating paste mixed with silverparticles to have electric conductivity. The silver paste is coated onthe passivation film while filling the through-holes, heated forsolidification to form a solid electric conductor. The silver paste maybe H20E (trade mark) supplied from Epotech Co.

Referring to FIG. 10, in the terminal area of a TFT panel of an activematrix LCD device, generally designated by numeral 10, according to afourth embodiment of the present invention, a plurality of scanninglines (not shown) are connected to respective scanning electrodes 14Aformed on a driver block or a COF (chip-on-film) 54, and then connectedto a vertical driver IC 54 b. In addition, the common lines (not shown)are connected to common electrodes 16A formed on the COF 54, and areconnected together via a coupling line 58 formed on a base film mountingthereon the vertical driver IC 54 b. The present embodiment is similarto the second embodiment, except for the coupling line 58 formed on theCOF in the present embodiment.

The structure of a typical COF 54 is exemplified in FIG. 11. The COF 54includes a base film 54 a, a vertical driver IC 54 mounted on the basefilm 54 a for driving the scanning lines, a plurality of input lines 54c connected to respective input terminals of the vertical driver IC 54b, and a plurality of output lines 54 d connected to respective outputterminals of the vertical driver IC 54 b.

The output lines 54 d correspond to the scanning electrodes 14A shown inFIG. 10. A solder resist film 54 e covers the input and output lines 54c and 54 d on the base film 54 a, and a plurality of bumps 54 f connectthe vertical driver IC 54 b and the input and output lines 54 e and 54d. The COF 54 may be such as supplied from Sony Chemical Corp.

Referring additionally to FIGS. 12 and 13, the scanning lines 14 areconnected to the vertical driver IC 54 b via the scanning electrodes14A, i.e., output lines 54 d, formed on the COF 54. In addition, thecommon lines 16 are connected together by the coupling line 58 via thecommon electrodes 16A formed on the COF 54. The coupling line 58 isformed on the base film 54 a, as shown in FIG. 12, within a spacebetween the vertical driver IC 54 b and the base film 54 a and betweenthe input terminals and the output terminals of the vertical driver IC54. In this configuration, the COF 54 does not have an opening, such asformed in a TCP which is describe later, and the coupling line 58 isformed in the space above the vertical driver IC 54 b.

In the above embodiment, the output lines 54 d of the COF 54, whichmounts thereon the scanning electrodes 14A, the common electrodes 16A,and the coupling line 58, is attached to the end terminals of thescanning lines 14 and the common lines 16 by thrusting the COF 54 towardthe glass substrate 12. FIG. 14 shows the final structure of connectionespecially in the vicinity of the COF 54, wherein the coupling line 58extends between the row of the output terminals and the row of inputterminals of the vertical driver IC 54 b. Thus, the active matrix LCDdevice of the present embodiment enables the number of photolithographicpatterning steps to be reduced by obviating formation of the couplingline overlying the common lines 16 and the scanning lines 14.

Referring to FIG. 15, a modification of the active matrix LCD device ofFIG. 7 is such that the terminals 59 of the scanning electrodes 14A arearranged in a zig-zag fashion. This arrangement of the terminals 59 ofthe scanning electrodes 14A allows the common electrodes 16A to pass ina crank space formed between adjacent scanning electrodes 14A. In thiscase, the vertical driver IC 54 b has an arrangement of bumpscorresponding to the arrangement of the terminals 59 shown in FIG. 15.

Referring to FIG. 16, the contact area of a TFT panel of an activematrix LCD device, generally designated by numeral 62, according to afifth embodiment of the present invention is similar to the secondembodiment of FIG. 5 except for a coupling line installed within thevertical driver IC 54 in the present embodiment. More specifically, thescanning lines 14 such as shown in FIG. 5 are connected to scanningelectrodes 14A formed on a driver block or a TCP 64, and then connectedto a vertical driver IC 64 c mounted on the TCP 64. The commonelectrodes 16A formed within the TCP 64 are connected to the innercommon electrodes formed inside the vertical driver IC 64 c andconnected together via an inner coupling line formed inside the verticaldriver IC 64 c.

A typical TCP 64 having an opening is exemplified in FIG. 17, wherein avertical driver IC 64 c is attached to the base film 64 a by a resin 64i at the opening 64 b formed in the base film 64 a. The base film 64 ahas thereon input lines 64 d for the vertical driver IC 64 c, and outputlines 64 e for the vertical driver IC 64 c. The input and output lines64 d and 64 e are adhered onto the base film 64 a by an adhesive 64 f,and covered by a solder resist layer 64 g. The input and output lines 64d and 64 e are connected to the vertical driver IC 64 c via bumps 64 h.The TCP 64 may be such that supplied from NEC Corp.

In the present embodiment, as shown in FIGS. 18 and 19, the scanningelectrodes 14A and the common electrodes 16A are connected to thevertical driver IC 64 c via the bumps 64 h. The common electrodes 16Aare connected together by the inner coupling line installed inside thevertical driver IC 64 c, whereas the scanning electrodes 14A is appliedwith a gate signal from the input lines 64 d by the control of thevertical driver IC 64 c.

The output lines 64 e of the TCP 64 including therein the verticaldriver IC 64 c, scanning electrodes 14A and the common electrodes 16Aare attached to the end terminals of the scanning lines 14 and thecommon lines 16 by thrusting the TCP 64 toward the glass panel 12 forelectric connection. The TCP 64 may be replaced by a COF such as 54 usedin the fourth embodiment. FIG. 20 shows the connection especially in thevicinity of the TCP 64.

Referring to FIG. 21, a pixel of the TFT panel shown in FIG. 2 isdisposed in the area defined by a scanning line 14, a correspondingcommon line 16 and adjacent two signal lines 17. The pixel includes aTFT having a gate electrode 19 implemented by a portion of the scanningline 14. Referring additionally to FIG. 22, the TFT, known as aninverted stagger TFT, has a semiconductor layer 27 including an islandamorphous silicon film 27A to which the gate electrode 19 opposes withan intervention of an underlying gate insulating film 25, and a pair ofn-type source/drain regions made of amorphous silicon films 27B formedon the island amorphous silicon film 27A. A source electrode 21B anddrain electrode 21A are formed on the respective n-type source/drainregions.

A comb-shape pixel electrode 22 and a comb-shape common electrode 23shown in FIG. 21 oppose each other in the pixel, with an intervention ofthe gate insulating film 25, as shown in FIG. 23. The pixel electrode 22and the common electrode 23 form therebetween a lateral electric fieldparallel to the glass substrate 12, thereby implementing an in-planeswitching (IPS) mode LCD device.

The scanning line 14, common line 16, common electrode 23 and gateelectrode 19 are formed by patterning a first level conductor layerincluding an Al film and an overlying TiN film. The signal line 17,drain electrode 21A, source electrode 21B are formed by patterning asecond level conductor layer including a Cr film and an overlyingtransparent ITO film. The signal line 17 is formed on an underlyingsemiconductor layer 27 which is configured to have the same pattern asthe signal line 17 and formed on the gate insulating film 25. The pixelelectrode 22 is made of the transparent ITO film, which extends tooppose the common line 16 with an intervention of the gate insulatingfilm 25, to thereby form an additional capacitor therebetween forassisting the LC element to store signal charge.

Now, a fabrication process for fabricating the active LCD device of thefirst embodiment will be described with reference to FIGS. 24A to 24K.

An Al film having a thickness of about 200 nm and a TiN film having athickness of about 500 nm are consecutively formed on a glass substrate12 by sputtering, thereby forming a first level conductor film. Thefirst level conductor film is then patterned by a photolithographicetching step to obtain: scanning lines 14 including scanning terminals20 and gate electrodes 19; common lines 16 including common electrodes23; and coupling lines 18 including common terminals 24A and 24B. Theresultant TFT panel after the etching is shown in FIGS. 24A to 24C.

Thereafter, a gate insulating film 25 made of silicon nitride having athickness of about 400 nm, a semiconductor layer 27 including anamorphous silicon film 27A having a thickness of 250 nm and an n-typeamorphous silicon film 27B having a thickness of 50 nm are consecutivelyformed on the surface of the resultant TFT panel by a plasma-enhancedCVD process. A metallic film made of Cr having a thickness of 250 nm isthen formed thereon by sputtering. The semiconductor layer and themetallic film are then consecutively patterned to obtain signal lines 17including signal terminals and interconnects extending from the signallines in the pixels. The resultant TFT panel after the etching is shownin FIGS. 24D to 24F.

A transparent conductor film made of ITO having a thickness of about 50nm is then formed on the resultant TFT panel. The transparent conductorfilm is then patterned by a photolithographic etching process to leaveportions thereof covering the signal lines 17, drain electrodes 21A,source electrodes 21B, and pixel electrodes 22. Portions of the metallicfilm exposed from the patterned transparent film are then removed byetching. The resultant. TFT panel after the etching is shown in FIGS.24G to 24I.

By using the patterned transparent conductor film (or the mask patternused for patterning the transparent conductor film) as a mask, exposedportions of the n-type amorphous silicon film 27B is then etched to forma channel gap. The resultant TFT panel is shown in FIGS. 24J and 24K.

Thereafter, a passivation film 26 made of silicon nitride having athickness of about 300 nm is formed on the resultant TFT panel by usinga plasma-enhanced CVD process. The passivation film 26 is then patternedto leave portions thereof covering the signal terminals, scanningterminals 20 and common terminals 24A and 24B, followed by patterningthe gate insulating film 25, thereby exposing the signal terminals madeof transparent conductor film, scanning terminals 20 and commonterminals 24A and 24B. Finally, an annealing process is conducted at atemperature of about 280° C. to complete the TFT panel having the pixelshown in FIGS. 21, 22 and 23.

In the embodiments as described above, although the first levelconductor layer exemplarily includes two-film layer including Al filmand TiN film, the first level conductor layer may include three filmssuch as TiN/Al/Ti films or two other films including Cr film andoverlying ITO film. The TiN film may be made of nitride of anotherhigh-melting-point metal instead, wherein the nitrogen concentration ispreferably above 25 atomic percents. The transparent conductor film maybe replaced by nitride of a high-melting-point metal, such as TiN.

Combination of any two of coupling lines described in the respectiveembodiments as described above may be employed. For example, a TFT panelmay include a first coupling line formed on the TFT panel outside thearea for the pixel array and a second coupling line including aconductive paste, or a second coupling line formed on the COF or TCP orin the vertical driver IC.

Since the above embodiments are described only for examples, the presentinvention is not limited to the above embodiments and variousmodifications or alterations can be easily made therefrom by thoseskilled in the art without departing from the scope of the presentinvention.

1. A liquid crystal display (LCD) device comprising a TFT panel, acounter panel and liquid crystal interposed therebetween, said TFT panelcomprising: a transparent substrate; a plurality of scanning linesoverlying said transparent substrate to extend in a row direction; aplurality of signal lines overlying said transparent substrate to extendin a column direction; a plurality of common lines each corresponding toone of said scanning lines to extend in said row direction parallel tosaid one of said scanning lines, said scanning lines and said commonlines are formed in a single layer so that at least one of said scanninglines and at least one of said common lines are arranged consecutivelyin said column direction and alternating from each other in parallel; anarray of pixels each disposed at an intersection between one of saidscanning lines and one of said signal lines; and a coupling lineextending in said column direction, said coupling line including aconductive paste or a conductive tape coupling said common linestogether.
 2. A liquid crystal display (LCD) device comprising a TFTpanel, a counter panel, and liquid crystal interposed therebetween, saidTET panel comprising: a transparent substrate; a plurality of scanninglines overlying said transparent substrate to extend in a row direction;a plurality of signal lines overlying said transparent substrate toextend in a column direction; a plurality of common lines eachcorresponding to one of said scanning lines to extend in said rowdirection parallel to said one of said scanning lines, said scanninglines and said common lines are formed in a single layer so that atleast one of said scanning lines and at least one of said common linesare arranged consecutively in said column direction and alternating fromeach other in parallel; and an array of pixels each disposed at anintersection between one of said scanning lines and one of said signallines, said TFT panel mounting thereon at least one driver blockincluding a film member, a driver IC mounted on said film member fordriving said scanning lines, and a coupling line for connecting saidcommon lines together, said coupling line extending in a space betweensaid film member and said driver IC.
 3. The LCD device as defined inclaim 2, wherein said film member is a chip-on-film (COF).
 4. The LCDdevice as defined in claim 2, wherein terminals of said scanning linesare arranged in a zig-zag fashion on said TFT panel.
 5. The LCD deviceas defined in claim 1, wherein said common lines are coupled togetherusing different coupling structures on a first side with respect tocoupling structures used on a second side of said substrate.
 6. The LCDdevice as defined in claim 2, wherein said common lines are coupledtogether using different coupling structures on a first side withrespect to coupling structures used on a second side of said substrate.